The present invention relates to a method of stretch-blow-moulding a beverage container and a method to dispense a beverage.
Stretch-blow-moulding of polyesters like polyethylene terephthalate from an injection-moulded preform has been known on a commercial scale since Nathaniel Wyeth at DuPont demonstrated the reheat process. AOKI and Nissei developed the injection blow-moulding technology into a viable alternative to the reheat and blow process. Such blow-moulded hollow articles are to a large extent used for the distribution of beverages, and PET bottles or containers have become generic items.
There are several problems associated with the technology:                Lack of barrier for water, CO2, and O2.        Lack of barrier for certain wavelengths of light, which can rapidly deteriorate the taste of the beverage.        Generation of the off taste ingredient acetic aldehyde, by deterioration of the polymer itself.        Cost of the polymer which has high value in other fields, such as electrical dielectric in capacitors and as the most important fabric fibre material for clothing and carpets.        
Some of the above problems may be solved by co-injection of the preforms in up to 7 layers. These are, after reheating, blown simultaneously in one step. Normally, it is of the highest importance to avoid delamination during this production process. Delamination not only reduces the strength of the beverage container, it also reduces the aesthetics of the beverage container.
The material used for the preform layers should preferably be any thermoplastics such as PET or polypropylene (PP). The use of metal or glass should be avoided due to increased recycling costs.
The blow-moulding process normally includes heating of the preform using an IR (infrared) lamp to make the preform deformable. The preform layers may have different absorption wavelengths. Therefore possibly a plurality of IR lamps, each having a separate peak intensity wavelength or wavelengths, may be necessary for heating the preform and making it deformable.
Alternatively, two layers or more layers may have the same absorption wavelengths and may thus be heated using the same IR lamp.
The layers may be dyed or otherwise treated for maximum absorption of a certain wavelength or wavelengths. Such treatment may comprise adding an absorption constituent such as aluminium dioxide or carbon black.
To avoid delamination an adhesive film may be applied between the different layers in the preform. The adhesive film is intended to increase the adhesion between the layer materials by the use of Van der Waal type physical adhesion.
To avoid influencing the material properties of the layers or influencing the properties of the beverage contained in the beverage container a chemical bond between the layers should be avoided.
The adhesive film should be flexible in order to be able to cover the complete interface between the thermoplastic layers as the walls of the preform are considerably stretched during the blow-moulding process. A single void in the film may lead to reduced adhesion, which may lead to delamination of the beverage container. Adhesive film material which may be used for the above purpose includes, e.g., nylon.
In some cases it may be desirable to have the possibility to delaminate a beverage container, i.e. in order to create a separate outer protective casing and an inner beverage bottle. A delaminated beverage container may be especially useful when handling a large amount of beverage together with a beverage dispensing system such as e.g. a water dispensing system or a draught beer dispensing system.
Conventional beverage dispensing systems operate with rigid containers made of e.g. glass, plastics or metal, filled with a beverage such as water, beer or the like. When dispensing the beverage a gas may be injected into the container to replace the drained beverage for pressure equalization and to aid dispensing. The gas may be injected with a high pressure, thereby acting to push out the beverage. Such principle is typical for a conventional beer dispensing system. The drawback of such system is the need for heavy steel containers, so called kegs, to withstand the high pressure. The gas may also be drawn into the beverage container by the under-pressure originating from the drainage of the beverage. Such principle is typical for a conventional water dispensing system. A common problem of the above principles is the need to inject gas into the beverage container from an external gas source, the gas source being either the ambient air or a high-pressurized gas bottle. This gas may affect and possibly degrade the beverage.
Novel dispensing systems, such as a DraughtMaster™ System produced by the applicant company are described in WO2007/019848, WO2007/019849, WO2007/019850, WO2007/019851 and WO2007/019853, avoid the above problem by working with a collapsible beverage container. The beverage container is made of a relatively thin thermoplastic material and is collapsed during dispensing by high-pressurized air. The beverage is thereby dispensed without any contact with the air. In this way no low pressure is generated and therefore there is no need for injecting gas into the beverage container.
The drawback of the above system is the need for relatively thin beverage containers, as they need to be collapsible. There is an apparent risk that such thin containers may burst, either during transportation of the beverage container or during dispensing as the beverage container is collapsed. A rupture of the beverage container will possibly lead to beverage leaking from the container and damaging external equipment and apparatus.